Re: DTP41 White Backing
Re: DTP41 White Backing
- Subject: Re: DTP41 White Backing
- From: Tom Beckenham <email@hidden>
- Date: Tue, 05 Mar 2002 12:28:03 +1100
The more I thought about this backing thing, the more I realized how complex
this issue is. How do you simulate the appearance of newspaper? What is the
"color" of newspaper? Paper is not a purely reflective media, it's also
transparent. The color of the paper depends on the background. How on earth
do we account for that? The more I thought about it I started to think that
separating reflective and transparent media for profiling purposes is really
somewhat flawed. There are standards for lighting, and we have light boxes
to simulate that. But are there standards for background? Are there
tables/mats that you should look at proofs on?
To get a totally accurate simulation, an instrument would need to measure
both reflectance AND transparency. Otherwise you would have to specify how
to view and compare proofs to press runs. If you used a black backing, you
would have to place a single sheet of newspaper on a black table next to the
proof. You couldn't look at a full newspaper with multiple pages and compare
the two. I'm not sure anything could simulate that. Also, with black backing
you couldn't put the newspaper on top of the proofing stock to compare side
by side.
Although black backing does seem to give you more control, especially with
double sided stuff, it does seem a little impractical. Not only would you
need a black table, but to run newspaper through a DTP41 you also need
flexible black backing to stick the newspaper on. Maybe you could just use
the built-in black square, but how black could it really be? Could you match
the black of the backing to the table?
So what about white backing? Really you have the same problems that you do
with the black backing. Plus you get the added problem of seeing through to
the other side of double sided prints. You couldn't get a 100% accurate
match unless you matched the background of the viewing table to the backing.
The only advantage of white backing is that proofing stock is "almost"
white. So when you sit your newspaper on proofing stock next to your proof,
it "seems" to match. This is probably going to make our clients happy. You
do also get a wider gamut, which may have a mathematical advantage, but I'm
not sure about that.
Thirdly, you also have the option of using multiple sheets of the same stock
as backing by putting several sheets together. This option probably has the
least control of all, but may give the best simulation of a multiple page
publication. Putting a whole bunch of sheets together does not give you the
"color of newspaper". Background + reflection (+ light + eye) = newspaper
color. What happens to the light after it travels through a page of
newspaper and hits another? That light hits the next sheet, some comes back,
the rest goes through. The "some that comes back" hits the back of the first
sheet, and again some comes back through and the rest reflects back. Using
this method will give a darker result than using a white backing. Plus, you
are now using a different backing for every stock you use. This means you
can't just place a sheet of newspaper next to a proof on a table, you need
to get a bunch of stock to put it on. You also have to renew that stock
quite often because of degradation.
At the moment, I'm leaning towards the white backing. Mainly because it is
too hard to get our clients (advertisers) to use a black table to view
proofs/runs. I always used white proofing paper as backing for the DTP41.
However I ran a few tests and found that I probably wasn't using enough
sheets. I needed at least 3 sheets of matte ink jet paper (Epson photo
quality). That gave me a white that was 3% lighter than not using any
backing.
I definitely think that using black would be a good idea, IF there were
standard black tables/backing commonly in use. How close could you get a
backing to L*=0 a*=0 b*=0?. I also think that for proofing, designers would
much rather see a brighter image than a darker one. But with re-education
I'm not sure they would mind.
I definitely want to keep an eye on this issue.
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